Wellington, Dec 17 NZPA - In the absence of a medical professional, iPhone users could soon be the best people to turn to if you're having a heart attack.

St John and Marker have released a free CPR application for the iPhone, the first developed for New Zealand.

It reminds users of the steps in CPR, so can be used by anyone helping a collapsed patient.

Digital service agency Marker approached St John with the idea and St John provided the CPR information.

Downloading it is easy and free, St John marketing manager Clare Wilson said.

"Sudden cardiac arrest kills many New Zealanders every year. We want to do all we can to save as many of these people as possible and downloading this CPR application may just save some lives."

But the public -- even iPhone users -- could still do with first aid training and regular refresher training, St John said.